Over the years skid steer loaders have been known as agile, compact vehicles with a high degree of maneuverability and a wide range of applications in the agricultural, industrial and construction fields. Exemplary of this type of vehicle is the utility loader depicted in Sperry New Holland publication No. 31653524-12-74 L.V.O. (1975), entitled "Sperry New Holland Utility Loaders". These vehicles usually include an engine, a boom assembly and an operators compartment mounted on a frame supported by four wheels. Coupled to the engine are a main drive system and a lift system for the boom assembly. The vehicle is maneuvered by driving the wheels on one side at a different speed and/or in a different direction from those on the other side resulting in a turning motion, the severity of which is determined by the relative speeds.
Typically the engine, which is rear mounted for counterbalancing effect, drives a pair of hydrostatic pumps coupled to left and right mounted hydrostatic motors. Wheels on the left and right sides of the vehicle are driven by the left and right mounted motors through gears, chains and sprockets. In one known control arrangement, motion is controlled by an operator seated within the operators compartment by moving a pair of hand operated control levers which are linked to the pumps. The extent to which each lever is moved in a forward direction from a neutral position controls the amount of fluid supplied in a forward direction to its respective motor, and therefore the speed at which the wheels on that side of the vehicle will rotate. Similarly, the extent to which a lever is moved in the reverse direction from the neutral position will control the speed at which the associated wheels rotate in the reverse direction.
As mentioned above, skid steer loaders include a boom assembly. This assembly generally comprises a pair of lift arms pivotally mounted to the main frame, or a support frame extending upwardly from the main frame. Attachments are usually mounted to the front of the lift arms. A separate hydraulic system is used to actuate the boom assembly via hydraulic lift cylinders which drive the lift arms. This system is also used to actuate one or two tilt cylinders which pivot the attachment with respect to the lift arms. In the control arrangement mentioned above, a pair of foot pedals in the front of the operator compartment control the flow of hydraulic fluid from a hydraulic pump to the lift and tilt cylinders.
In addition to material handling buckets, various other attachments such as snow blowers, trenchers, tree spades and augers which include their own hydraulic motors are commonly mounted to the boom assembly. An auxiliary hydraulic system is used to control the flow of hydraulic fluid between the hydraulic pump and the hydraulic motor of the front mounted attachment. It is common in prior art systems, using the arrangement mentioned above, for the flow of hydraulic fluid to the motor to be controlled by an auxiliary spool valve through actuation of a handle on one of the control levers. The handle is normally biased to a neutral position. Pushing the handle in one direction strokes the auxiliary valve in a first direction, thereby causing hydraulic fluid to flow to the front mounted attachment in a first direction. Pushing the handle in the opposite direction strokes the auxiliary valve so as to supply fluid in a reverse direction.
In another known control arrangement flow of hydraulic fluid to the lift and tilt cylinders is controlled by a pair of handles on the control levers. Movement of one handle relative to its respective lever controls the boom lift cylinders and movement of the other handle relative to its respective lever controls the bucket tilt cylinders. In this arrangement, if an auxiliary hydraulic system is used for controlling a hydraulic motor or cylinder for mounted attachments, then a foot pedal is utilized for operator actuation.
Over the years, operators have become accustomed to one or the other arrangements, i.e., either using hand controls or foot controls to operate the bucket tilt and boom lift functions of skid steer loaders. In fact the method of operation becomes second nature and operators are reluctant to change to a different machine if it uses an arrangement with which they are not familiar. This becomes a problem for rental and leasing companies in that it requires that they stock different machines to be sure they can satisfy a broader customer base.
In all known prior art apparatus of which applicants are aware there is no simple, convenient system for quickly converting a skid steer loader foot control arrangement to a hand control arrangement, and visa-versa, to satisfy the demands of experienced operators.